The T2K (Tokai to Kamioka) experiment pLong-baseline (295km) neutrino oscillation experiment

Generate nm beam at J-PARC in Tokai

Detect the neutrinos with Super-K in KamiokaFirst application of off-axis beamgraphitetargetπ+ on-axis ν beam
2.5°

off-axis ν beam

on-axis detector
295km
off-axis detector

Goals

First observation of nm→ ne (measurement of θ13)Super-K

2Precise measurement of nm disappearance (θ23, Δm23)

Main Island of JapanINGRID (Interactive Neutrino GRID)

On-axis neutrino detector (16 identical modules) to monitor the beam direction

Veto plane

Unable to detect particles other than muon from neutrino interactions

10m

Bundle ofMPPC cables

Power supplyElectronics box

New additional on-axis neutrino detector in front of the central INGRID moduleiron1203mmνμ+n→μ-+p (MC)772mm

Better understand neutrino interactions in INGRID by detecting particles such as
hadrons and low-energy muons that INGRID is unable to detectμ-1203mm
Shading panels→ Reduce the uncertainty of neutrino interactions & cross sections

DesignRequirement
Reconstruct tracks of all kinds of charged particles from neutrino interactions

Identify the kinds of the charged particles from dE/dx

Sufficient number of neutrino events

scintillator

CCQE event in Proton Module

Veto planes

Motivations

Identify neutrino interaction mode.

Front ofmodule

Scintillator plane
Iron plane

INGRID proton module

Vetoplane

Beamcenter(i.e. protons & pions stop in iron layers) → Unable to indentify neutrino interaction modes

μ-Sandwich structure of iron target and scintillator tracking planes
High statistics because of large target mass (116 tons)



CCQE event in INGRID
νμ+n→μ-+p (MC)6mm

Tracking planes

scintillator
Scintillator
Fiber

34 scintillator tracking planes (without iron)One tracking plane consists of 32 scintillator bars



Fiber-MPPC(multi-pixel photon counter) readout# of channels:1204, target mass 556kg, size:1.42x1.42x0.96m3

MPPC

Fiber connector

Construction
0.before assembly 1.install scintillators

2.install fibers

3.install MPPCs

4.connect board and MPPCs with cables
Front end boards

CablesScintillator

Beam commissioning
Event display of beam data

Veto plane6.completion
Power supply
Electronics boxCables

FiberGrooves
for scintillators

5.install veto planes

Fiber connector

Front end board(ADC & TDC etc)

MPPCCCQE (νμ+n→μ-+p) candidate
Side view
Top view

Shading panels

CC1π+ (νμ+p→μ-+p+π+) candidate
Side view
Top view

NC elastic (νμ+p→νμ+p) candidate
Side view
Top view

Scintillator for tracking plane
Scintillator for veto plane
Hit in scintillator(Size corresponds to light yield)
Reconstructed track

Timing distribution# of events vs # of protons on target

7Expectedtime# of hits > 10p.e.

Gain×105654# of events after selection

MPPC gain stability

3Time from trigger (ns)

Data
MC

POT normalized

Data
MC

→ Beam data is taken stably

POT normalized# of events

Select events whose vertices ofreconstructed tracks are in fiducial
volume. This is very preliminary result.

# of events

Vertex distribution after selection# of events→ 8 bunches distribution can be seen clearlyand events are observed in expected time

→ MPPCs are working stably# of protons on target

POT normalized

Data
MCTo do•Estimate background with MC•Use tuned neutrino flux
•Tune detector MC with data
•Update analysis method

Thick region

Vertex X (cm)Thick region

vertex Y (cm)Vertex Z (cm)We are successfully taking beam data and study is directed toward first physics result.